A color light blocking agent is mainly consisted of a pigment disperse liquid, an alkali soluble film-forming resin, a multi-functional monomer and a photo-initiator (see Chinese Patent Application CN101613276A). The methacrylic resin is a film-forming resin generally used in a color light blocking agent, and has high transparency and resolution. There are double bonds in a certain proportion on the side chain of the methacrylic resin, and thus, a polymerization under the action of a radical polymerization initiator may happen among the polymer chains, or a cross-linking reaction with small molecules may happen. Generally, the double bonds introduced are methacrylic double bonds and the polymerization thus happened is a radical polymerization. However, the radical polymerization is apt to be interfered by the polymerization inhibition of oxygen, resulting in the decreased sensitivity and poor developing property of the color light blocking agent sometimes.